[tor-bugs] #28849 [Core Tor/Tor]: Handle dormant mode in process library and for PT's

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#28849: Handle dormant mode in process library and for PT's
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 Reporter:  ahf           |          Owner:  (none)
     Type:  enhancement   |         Status:  new
 Priority:  High          |      Milestone:  Tor: unspecified
Component:  Core Tor/Tor  |        Version:  Tor: unspecified
 Severity:  Normal        |     Resolution:
 Keywords:  041-proposed  |  Actual Points:
Parent ID:                |         Points:
 Reviewer:                |        Sponsor:  Sponsor19
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Comment (by dcf):

 In the [http://meetbot.debian.net/tor-meeting/2019/tor-
 meeting.2019-05-09-17.01.html anti-censorship meeting today], we
 brainstormed two potential designs for communicating dormant mode with
 PTs:

 1. A ''startup'' mode, where the PT declares during the initial exchange
 with tor, "I support dormant mode," and thereafter tor implicitly assumes
 that the PT becomes dormant when requested to do so.
 2. An ''acknowledgement'' mode, where tor sends a command to the PT to
 enter/leave dormant mode, and the PT responds with a message saying "OK, I
 am entering/leaving dormant mode." If the PT doesn't send such an
 acknowledgement, it means the PT doesn't support dormant mode.

 Here's a third potential design to think about:

 3. An ''asynchronous'' mode, where both tor and PT send each other
 messages that are (at the protocol level) purely advisory: "I am entering
 dormant mode" and "I am leaving dormant mode." Of course the PT would take
 tor's "I am entering dormant mode" as a hint to enter dormant mode itself,
 but there would be no protocol-level binding between the messages: each
 side is merely keeping the other informed about its current status.

 It could be a good first use of the [ticket:28181 STATUS] feature. The
 PT→tor messages could look like
 {{{
 STATUS TRANSPORT=whatever DORMANT="on"
 STATUS TRANSPORT=whatever DORMANT="off"
 }}}

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/28849#comment:6>
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